Mobile expandable structure designs to date have basically tried to provide a ready-made, weather resistant volume of space. Heating systems, electrical power, water storage and disposal systems, if provided at all, would typically be addressed in a fashion similar to recreational type vehicles and/or require fixed utility connections. Some mobile structures utilizing after market solar panel products may require breaching of the roofing membrane for installation affecting weather resiliency of the structure. The panels, being attached to the roof also remain vulnerable to theft and the elements when not in use. Additionally, the panels are not readily re-directed for optimal solar gain without repositioning of the structure, which may not always be possible.
After market systems are typically not adequate to fully support the electrical requirements of extended deployments as dependence remains on 12-volt systems that need to be re-charged via petroleum-fueled generators and/or by connection to an electrical feed. Holding tanks for fresh, ‘gray’ or ‘black’ water require periodic servicing that may require travel to a dumpsite requiring retraction of the deployed structure. Additionally, current construction techniques and finishes can lead to or cause deleterious interior air quality such as molds or off gassing from materials.
Inventions to date have not fully addressed a lightweight, mobile expandable structure design that incorporates the use of sustainable features and other techniques to allow for extended periods of deployment while increasing user comfort and ease of use.
Both U.S. Pat. No. 5,061,101 to Madden; Maginnis (1991) and U.S. Pat. No. 6,712,414 to Morrow (2004) present expandable systems. U.S. Pat. No. 5,061,101 utilizes a base enclosure assembly with retractable modules that extend out from the base assembly. While U.S. Pat. No. 6,712,414 shows opposing side sections that can be retracted, similar to “pop-outs or slide-outs” in the recreational vehicle industry. The width of the retractable portions is often limited to half the width of the base assembly, if not less, due to the complicated mechanical and structural requirements. Consequently, designs such as this can offer only an approximate doubling of overall floor area in the deployed condition. The dual sided design also makes access to, or through the core structure difficult if not impossible during transport.
An increase in relative floor area is shown in U.S. Pat. No. 4,603,518 to Fennes (1986). Here a collapsible mobile building is shown. The increase in size is accomplished by pivotally connecting the collapsible portions to the fixed base. Using motors, the collapsible units travel through an approximate 90° arc where they are subject to racking loads due to the designs geometry. Once in place, the collapsible units have roofs that are higher than the central base unit making for uncertain weather protection issues along the longitudinal interfaces of the fixed and collapsible portions. Also, the conveyance is shown using a heavy-duty tractor-trailer type rig for transport. The increased floor areas of this design would also be subject to the increased effects of wind loading such as ‘uplift’ forces on the structure.
U.S. Pat. No. 4,534,141 to Fagnoni (1985) and U.S. Pat. No. 5,996,956 to Morris: Rogers (1999) show an alternative means of deployment to the patents mentioned above. However, both patents are not shown to be independently mobile, via mounting to a permanent wheeled conveyance, U.S. Pat. No. 4,534,141 shows substantial longitudinal base beams that are integral to the floors longitudinal frame requiring the support of a foundation such as a concrete slab or pad footings as there are no means for terrain adjustments along this central support core. Additionally, the longitudinal fixed frames of the walls are primarily solid and allow for only nominal passage to the deployed areas that are on either side of the core thus reducing floor plan flexibility. Gutters are shown in the detailed views but do not offer a means to use or store collected water. Insulation of the structure is also greatly compromised at the junctures of the foldable roof connection to the eave walls creating a poor thermal condition at a critical area of any heated structure.
U.S. Pat. No. 5,996,956 shows a portable refrigerated storage unit that may function as a structure or a mortuary in emergency situations. The unit is designed for shipping and transporting in a standard cargo-shipping container. Shipping container size constraints limit the structures interior height and volume when deployed; this may impinge on the users overall well being if the structure is to be used for extended periods.
The design also utilizes steel for both the skin and structural elements, making for a heavy overall weight. The design shows the foldable floor, wall and roof panels each being deployed in two segments requiring additional trim and flashing pieces to be installed at their common junctures. Other individual parts are also shown that need to be separately installed to complete the deployment. If these pieces are not installed properly or the pieces or lost or misplaced, the structure may not function properly affecting weather resiliency; which if compromised, may lead to an uncomfortable interior environment and possible health issues as well as adversely affecting the structural integrity of the structure.
In conclusion, insofar as I am aware, no self-sustaining, mobile, expandable structure developed provides the mobility of a lightweight wheeled conveyance that can expand easily to approximately three times the area of the unit in transport, requiring no motors or mechanized tools and can provide protection from wind up-lift forces while providing extensive water fresh and grey water handling capabilities.